Fiber composite part of a motor vehicle, mounting part for such a fiber composite part and manufacturing method

ABSTRACT

A mounting part ( 11 ) for affixing a composite fiber part of a motor vehicle to at least one adjoining component of a motor vehicle is made from a fiber composite material. The mounting part ( 11 ) has a three-dimensionally shape that defines ribs and/or webs and/or protrusions and/or depressions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 USC 119 to German Patent Appl.No. 10 2012 102 290.9 filed on Mar. 19, 2012, the entire disclosure ofwhich is incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The invention relates to a mounting part for affixing a fiber compositepart of a motor vehicle to at least one adjoining component of the motorvehicle. Furthermore, the invention relates to a fiber composite part,to a method for manufacturing the mounting part and to a method formanufacturing the fiber composite part.

2. Description of the Related Art

Fiber composite parts made from carbon fiber reinforced or glass fiberreinforced polymers are increasingly used in motor vehicles to achieveweight reductions. However, it is necessary to connect the fibercomposite parts to at least one adjoining component of the motorvehicle. Mounting parts, or inserts, incorporated in the respectivefiber composite part to connect the fiber composite parts to theadjoining component. According to the prior art, these mounting partsincorporated in a fiber composite part are metallic, and usuallyaluminum.

The metallic mounting part used for affixing the fiber composite part toan adjoining component of the motor vehicle must be coated with anadhesion promoter and an anti-corrosion agent prior to being introducedinto the fiber composite part. As a result, manufacturing expenses areincreased.

Fiber composite parts used with metallic mounting parts are disclosed inWO 2011/051227 A1.

An object of the present invention is to provide an innovative mountingpart for affixing a fiber composite part of a motor vehicle to at leastone adjoining component of the motor vehicle, an innovative fibercomposite part and a method for manufacturing the mounting part and thefiber composite part.

SUMMARY OF THE INVENTION

The invention relates to mounting parts that are incorporated orembedded in a fiber composite part for affixing the fiber composite partto an adjoining component. The mounting parts of the invention are madefrom a fiber composite material. As a result, and unlike the prior art,there is no need to coat the mounting parts with an adhesion promoterand an anti-corrosion agent prior to being incorporated, therebyreducing manufacturing expenses. Moreover, the fiber composite mountingparts ensure an integral bond between the mounting parts and the fibercomposite part.

The mounting part is made from a carbon fiber reinforced or a glassfiber reinforced polymer with relatively short fibers between 3 mm and100 mm in length, and preferably between 20 mm and 80 mm in length. Thisdefined length of the relatively short fibers for the mounting partallows on the one hand the guarantee of a sufficient strength of themounting part, and on the other hand the provision of athree-dimensional shape analogous to that of metallic mounting parts.

The mounting part preferably comprises between 30% by volume and 70% byvolume, in particular between 40% by volume and 65% by volume, fibersand furthermore between 70% by volume and 30% by volume, in particularbetween 60% by volume and 35% by volume, a thermosetting polymer. Thiscomposition of the mounting part of fibers and thermosetting polymer isadvantageous for guaranteeing a high strength of the mounting parts.

The mounting part preferably is manufactured by preparing a liquid orflowable mixture of polymer and fibers. The mixture then is filled intoa three-dimensionally shaped mold for the mounting part. The mold thenis closed and the mounting part is cured for a defined period of time ata defined temperature and a defined pressure. The aforementioned methodenables the manufacturing of three-dimensionally shaped mounting partswith sufficient strength from a fiber composite material with simplemeans. In this context the term “flowable” does not mean that themixture has to be “flowable” already at room temperature. Rather, themixture may take the form of a sheet at room temperature and anappropriately weighed amount may be filled into the mold. The mixtureconforms to the three-dimensionally shaped mounting part once the moldhas been closed on the basis of temperature and pressure.

The mounting part preferably is cured in the mold for a period ofbetween 0.5 min and 10 min at a temperature between 100° C. and 200° C.and at a pressure of more than 100 bar. The abovementioned processparameters are advantageous, with the tool preferably being heatedisothermally during the curing of the mounting part.

Exemplary embodiments of the invention are explained with reference tothe drawing, without being limited to this.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a detail of a fiber composite part of a motor vehicleaccording to the invention in cross section in the region of anincorporated mounting part.

FIG. 2 is a first mounting part in different perspective views.

FIG. 3 is a second mounting part in different perspective views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates to a mounting part for affixing a fiber compositepart of a motor vehicle to at least one adjoining component of the motorvehicle. The mounting part is incorporated or embedded in the respectivefiber composite part and is referred to as an insert. The invention alsorelates to a fiber composite part of a motor vehicle with at least onesuch mounting part and to a method for manufacturing the mounting partand the fiber composite part.

FIG. 1 is a partial schematic cross section through a fiber compositepart 10 of a motor vehicle in the region of a mounting part 11incorporated or embedded in the fiber composite part 10. The mountingpart 11 is provided for affixing the fiber composite part 10 to at leastone adjoining component.

A recess 12 with an internal thread 13 is cut into the mounting part 11to allow a direct screw connection of the fiber composite part 10 viathe mounting part 11 to an adjoining component. Alternatively, aninternally threaded bush can be inserted into the recess 12 so that thefiber composite part 11 can be screwed indirectly via the threaded bushto an adjoining component.

The mounting part 11 incorporated in the fiber composite part 10 is athree-dimensionally shaped structure with ribs, and/or webs and/orprotrusions and/or depressions. FIGS. 2 and 3 show in differentperspective views examples of three-dimensionally shaped mounting parts11′ and 11″ formed with ribs 14, webs 15, protrusions 16 and/ordepressions 17.

The mounting parts 11, 11′ or 11″ for a fiber composite part are madefrom a fiber composite material, namely from a carbon fiber reinforcedor a glass fiber reinforced polymer with relatively short fibers. Thecarbon fiber reinforced or glass fiber reinforced polymer is preferablya thermosetting polymer, in particular an epoxy resin or a vinyl-esterresin or polyurethane.

The relatively short fibers of the mounting part 11, 11′ or 11″ have alength of between 3 mm and 100 mm. Preferably, the length of therelatively short fibers of the mounting part 11, 11′ or 11″ is between20 mm and 80 mm.

The mounting part 11, 11′ or 11″ may have fibers of exclusively onelength, such as short fibers exclusively of a length of 25 mm or 70 mmor 75 mm. Alternatively, the respective mounting part 11, 11′ or 11″ mayhave relatively short fibers of at least two different lengths, forexample first fibers of a length of 25 mm and second fibers of a lengthof 50 mm. Likewise it is possible that the mounting part 11, 11′ or 11″has first fibers of a length of 10 mm and second fibers of a length of75 mm.

The use of fibers of different lengths for the mounting partadvantageously enables both a sufficient strength of the respectivemounting part 11, 11′ and 11″ and any desired three-dimensional shapingof the part.

The respective mounting part 11, 11′ or 11″ preferably has between 30%by volume and 70% by volume fibers and between 70% by volume and 30% byvolume thermosetting polymer.

The mounting part 11, 11′ or 11″ preferably comprises between 40% byvolume and 65% by volume fibers and between 60% by volume and 35% byvolume thermosetting polymer, in particular epoxy resin.

The mounting parts 11, 11′ or 11″ for a fiber composite part 10 of amotor vehicle themselves uniquely are made from a fiber compositematerial. In this context relatively short fibers in a defined mixingratio with a polymer are used in the respective mounting part 11, 11′ or11″. Thus, three-dimensionally shaped mounting parts made from a fibercomposite material are provided with a three-dimensional shape typicallyassociated with metallic mounting parts and with a sufficiently highstrength.

The fiber composite parts 10 and the mounting parts 11, 11′ or 11″incorporated therein preferably are made from a fiber compositematerial, with identical fiber material of different lengths and with anidentical polymer material, such as thermosetting polymer, being used inthe fiber composite part 10 and in the mounting part 11, 11′ or 11″. Thefibers of the fiber composite part 10 are relatively long continuousfibers, namely relatively long carbon fibers or glass fibers.

The manufacturing of the mounting part 11, 11′ or 11″ proceeds bupreparing a liquid, in particular a viscous or flowable mixture ofpolymer and fibers. This mixture preferably comprises between 30% byvolume and 70% by volume fibers and the rest polymer, in particularthermosetting polymer. The preferred mixture comprises between 40% byvolume and 65% volume fibers and the rest polymer, such as epoxy resin.

This mixture is weighed and the weighed mixture is filled into athree-dimensionally shaped mold for the mounting part. The mold for themounting part 11, 11′ or 11″ then is closed and the mounting part iscured in a molding process with a heated mold. The curing in the moldtakes place at a defined temperature and at a defined pressure over adefined period of time. In particular, the curing of the mounting part11, 11′ or 11″ takes place in an isothermically heated mold at atemperature between 100° C. and 200° C. and at a pressure of more than100 bar over a period of between 0.5 minutes, that is to say 30 seconds,and 10 minutes.

The manufactured mounting parts 11, 11′ or 11″ are placed in an uncuredfiber composite matrix to form a semi-finished product. Thissemi-finished product may be a so-called prepreg of fibers andthermosetting polymer or a dry semi-finished product consisting of onlyfibers, into which, subsequent to the positioning of the mounting parts,thermosetting polymer, in particular epoxy resin, is injected. The fibercomposite matrix with the incorporated or embedded and already curedmounting parts 11, 11′ or 11″ then is cured, and the mounting parts 11,11′ or 11″ forming an intimate bond with the identical polymer materialof the fiber composite matrix to form a composite part 10.

What is claimed is:
 1. A mounting part for affixing a fiber compositepart of a motor vehicle to at least one adjoining component of the motorvehicle, the mounting part being made from a fiber composite materialand having a three-dimensionally shape with at least one of a rib, aweb, a protrusion and a depression.
 2. The mounting part of claim 1,wherein the mounting part is made from a carbon fiber reinforced or aglass fiber reinforced polymer.
 3. The mounting part of claim 2, whereincarbon fiber reinforced or a glass fiber reinforced polymer has fibersof between 3 mm and 100 mm in length.
 4. The mounting part of claim 3,wherein carbon fiber reinforced or a glass fiber reinforced polymer hasfibers of between 20 mm and 80 mm in length.
 5. The mounting part ofclaim 3, wherein the fibers are of one length.
 6. The mounting part ofclaim 3, wherein the fibers are of at least two different lengths. 7.The mounting part of claim 1, wherein the mounting part comprisesbetween 30% by volume and 70% by volume fibers and between 70% by volumeand 30% by volume a thermosetting polymer.
 8. The mounting part of claim7, wherein the mounting part comprises between 40% by volume and 65% byvolume fibers and between 60% by volume and 35% by volume athermosetting polymer.
 9. A composite part of a motor vehicle,comprising at least one mounting part made from a fiber compositematerial and incorporated or embedded in the fiber composite matrix foraffixing the composite part to at least one adjoining component of themotor vehicle, the mounting part defining three-dimensional shape withat least one of a rib, a web, a protrusion and a depression.
 10. Thefiber composite part of claim 9, wherein the fiber composite matrix ismade from a carbon fiber reinforced or a glass reinforced compositematerial.
 11. The fiber composite part of claim 10, characterized inthat the fiber composite matrix and the mounting parts are made fromidentical fiber material but of different lengths, and from an identicalthermosetting polymer material.
 12. A method for manufacturing amounting part for embeddment in a fiber composite matrix to define acomposite part of an automobile, the method comprising: preparing aliquid or flowable mixture of polymer and fibers, filling the mixturebeing into a three-dimensionally shaped mold for the mounting part,closing the mold, and curing the mounting part for a defined period oftime at a defined temperature and a defined pressure.
 13. The method ofclaim 12, wherein the curing step comprises curing the mounting part inthe mold for a period of between 0.5 min and 10 min at a temperaturebetween 100° C. and 200° C. and at a pressure of more than 100 bar. 14.The method of claim 12, wherein the liquid mixture or the mixture withflowing characteristics comprises between 30% by volume and 70% byvolume fibers and between 70% by volume and 30% by volume thermosettingpolymer, with the fibers having lengths of between 3 mm and 100 mm. 15.The method of claim 14, wherein the liquid mixture or the mixture withflowing characteristics comprises between 40% by volume and 65% byvolume fibers and between 60% by volume and 35% by volume thermosettingpolymer, with the fibers having lengths of between 20 mm and 80 mm. 16.The method of claim 12, further comprising placing the cured mountingparts in the fiber composite matrix in an uncured state and then curingthe fiber composite matrix around the cured mounting part to form fibercomposite part for the automobile.